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Ocular Manifestations of Systemic Disease

Kathern E. Myrna, DVM, MS, DACVO, University of Georgia


July/August 2021
Peer Reviewed

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Understanding the connection between ocular clinical signs and systemic disease can help in identification of underlying disease processes and ensure ocular concerns are addressed when managing known disease that may affect the eyes.

Ophthalmologic examination can be performed using simple equipment or cell phone photography and should include a Schirmer tear test, fluorescein stain, and measurement of intraocular pressure. Retroillumination entails use of a flash photograph or a light source at arm-length distance from and eye level of the patient and can help distinguish cataracts from age-related nuclear sclerosis. True cataracts should block the glow from the tapetal reflection. In addition, retroillumination can be used to help identify the location of opacities (eg, corneal pigment, vitreal changes).

Using a bright, focal light source (eg, direct ophthalmoscope, transilluminator) in a dark room is necessary to assess the cornea and anterior chamber. Illumination of the eye from the front, from the side, and at a 45-degree angle provides the best opportunity for visualizing all defects. Sharply focusing the smallest circle or the slit beam on the direct ophthalmoscope can help determine whether the aqueous humor in the anterior chamber is clear. Similar to the brain, the eye is protected from systemic circulation through the blood–eye barrier (anterior and posterior). Uveitis results in a breakdown of this barrier, allowing inflammatory cells, protein, and organisms into the eye. This manifests as flare (protein), hyphema (blood), or hypopyon (WBCs) in the anterior chamber. Anterior uveitis is also associated with scleral injection, low intraocular pressure (<10 mm Hg), and miosis.

The fundus is the most challenging area to examine; dilation prior to examination typically improves visualization. Indirect ophthalmoscopy using a handheld lens enables a more complete view of the retina but can be difficult to perform, as it requires a handheld lens and precise alignment of the light, lens, and eye to get a full image. Direct examination with an ophthalmoscope or a panoptic ophthalmoscope can potentially help identify inflammation in the fundus.

The following images illustrate various diseases and conditions; many were diagnosed using the aforementioned techniques. Some findings are nonspecific, and others are suggestive of specific disease.


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